Atomic layer or cyclic plasma etching chemistries and processes

ABSTRACT

Atomic layer or cyclic plasma etching chemistries and processes to etch films are disclosed. Films include Si, Ti, Ta, W, Al, Pd, Ir, Co, Fe, B, Cu, Ni, Pt, Ru, Mn, Mg, Cr, Au, alloys thereof, oxides thereof, nitrides thereof, and combinations thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 62/009,484 filed Jun. 9, 2014, herein incorporatedby reference in its entirety for all purposes.

TECHNICAL FIELD

Atomic layer or cyclic etching chemistries and processes to etch filmsare disclosed. Exemplary films may include mask films, such asTi-containing films, Ta-containing films, W-containing films, orAl-containing films. Exemplary films may alternatively include metalfilms, such as Pd, Ir, Co, Fe, B, Cu, Ni, Pt, Ru, Mn, Mg, Cr, Au, alloysthereof, oxides thereof, nitrides thereof, or combinations thereof.

BACKGROUND

Atomic layer etching is a cyclic dry etching process used in thesemiconductor manufacturing industry to remove one layer of the materialto be etched per cycle.

Many etchants have been disclosed for use in continuous (i.e.,non-cyclic) etch process. See, e.g., US2015/011093 and US2015/017810.

Many initial processes use a plasma etch gas cycle followed by a plasmainert gas cycle. For example, the December 2013 issue of Solid StateTechnology magazine discusses an atomic layer etching process of asilicon layer using chlorine (Cl₂) and Argon (Ar). U.S. Pat. No.4,756,794 discloses an atomic layer etching method to remove diamond byNO₂ followed by ion bombardment. Agarwal and Kushner presented thecomputer simulated results of atomic layer etching of a Si layer using acycle of Cl₂/Ar followed by Ar alone and atomic layer etching of a SiO₂layer using a cycle of c-C₄F₈/Ar followed by Ar alone (Plasma AtomicLayer Etching Using Conventional Plasma Equipment at the 53^(rd) AVSSymposium in November 2006). CN103117216 discloses an atomic layeretching method to remove an oxide or gate dielectric layer using afluorocarbon gas (C_(x)F_(y), specifically CF₄) mixed with an inert gas(Ar) followed by Ar. US2014/206192 discloses an atomic layer etchingmethod to remove graphene using O-based (such as CO₂, O₂, NO₂), F-based(such as C₄F₈, CF₄, or CHF₃), H-based (such as H₂, NH₃, or SiH₄) gasplasmas, or combinations thereof, followed by an energy source (such asneutral beam, ionic beam, heat energy, plasma, laser, or combinationsthereof). The neutral beam may contain He, Ar, N₂, Ne or Xe.KR20110098355, KR101465338, and KR101466487 disclose atomic layeretching methods using BCl₃ followed by irradiation by Ar or Ne ion beamor neutral beam to remove single layers of HfO₂/ZrO₂/Ta₂O₅; Al₂O₃, orBeO; respectively. U.S. Pat. No. 8,617,411 discloses an atomic layeretching method using Cl₂, HCl, CHF₃, CH₂F₂, CH₃F, H₂, BCl₃, SiCl₄, Br₂,HBr, NF₃, CF₄, SF₆, O₂, SO₂, COS, etc., followed by an inert gas (Ar,He, Kr, Ne, Xe, etc).

However, as these methods do not always remove the layer in asatisfactory manner, additional variations of atomic layer etching havebeen developed. For example, Lee and George disclose atomic layeretching of Al₂O₃ using sequential, self-limiting thermal reactions withSn(acac)₂ and HF (ACS Nano, 2015, 9 (2) pp. 2061-2070). JP58098929 toSeiko Epson Corp. discloses an atomic layer etching method to removeSiO₂ from a Si substrate by HF followed by I₂. U.S. Pat. No. 8,633,115disclosed an atomic layer etching process to remove SiO₂ by introducingH₂O or NH₃ followed by HF and a temperature change. U.S. Pat. No.8,124,505 discloses a two stage plasma technique using oxygen to oxidizethe surface of the aluminum gallium nitride barrier layer followed byusing BCl₃ to remove the oxidized layer.

A need remains for more precise dry processes to selectively removelayers without damaging the surrounding materials or leaving significantresidue on the substrate.

Notation and Nomenclature

Certain abbreviations, symbols, and terms are used throughout thefollowing description and claims, and include:

As used herein, the term “etch” or “etching” refers to a plasma orthermal etch process (i.e., a dry etch process). “Plasma etch” refers toion bombardment accelerating the chemical reaction in the verticaldirection (Manos and Flamm, Plasma Etching An Introduction, AcademicPress, Inc. 1989 pp. 12-13). “Thermal etch” refers to heat activatingthe chemical reaction on the reactive surface of a substrate. Thedisclosed etching processes may (a) remove deposits from chamber walls,(b) remove a mask or patterned layer from a substrate after patterning,or (c) produce apertures, such as vias, trenches, channel holes, gatetrenches, staircase contacts, capacitor holes, contact holes, etc., inthe substrate.

As used herein, the term “dry” means the vapor phase of a material.“Dry” is not used herein to directly address the water content of anymaterial, even though the water content of the disclosed materials isvery low. In other words, any “dry” material referenced herein is in itsvapor phase, notwithstanding the amount of water present in thematerial.

As used herein, the term “purge”, “purged”, or “purging” means to removethe gaseous contents of the chamber by using an inert gas and/or avacuum.

As used herein, the term “atomic layer etch” means removing one atomiclayer of a semiconductor material at a time. Atomic layer etch has beenreferred to as reverse atomic layer deposition.

The term “pattern etch” or “patterned etch” refers to etching anon-planar structure, for example by placing a patterned mask layer on astack of metal- and/or silicon-containing layers and etching vias ortrenches or the like in the areas not covered by the mask. The term“mask” refers to the layer that resists etching. The mask layer may belocated above or below (i.e., the etch stop layer) the layer to beetched. The mask layer may be a hardmask, such as TiN or TaN, or a softmask, such as a polymer or other organic “soft” resist materials. A“sacrificial mask” material is a material that is used to pattern asubstrate and then removed.

The term “selectivity” means the ratio of the etch rate of one materialto the etch rate of another material. The term “selective etch” or“selectively etch” means to etch one material more than anothermaterial, for example, to selectively etch the mask material from thesubstrate, or in other words to have a greater or less than 1:1 etchselectivity between two materials.

As used herein, the indefinite article “a” or “an” means one or more.

As used herein, the terms “approximately” or “about” mean±10% of thevalue stated.

As used herein, the term “pulsing” means both introducing the gaseouscompound into and removing the gaseous compound from the chamber.

As used herein, the term “independently” when used in the context ofdescribing R groups should be understood to denote that the subject Rgroup is not only independently selected relative to other R groupsbearing the same or different subscripts or superscripts, but is alsoindependently selected relative to any additional species of that same Rgroup. For example in the formula MR¹ _(x) (NR²R³)_((4-x)), where x is 2or 3, the two or three R¹ groups may, but need not be identical to eachother or to R² or to R³. Further, it should be understood that unlessspecifically stated otherwise, values of R groups are independent ofeach other when used in different formulas.

As used herein, the term “alkyl group” refers to saturated functionalgroups containing exclusively carbon and hydrogen atoms. Further, theterm “alkyl group” refers to linear, branched, or cyclic alkyl groups.Examples of linear alkyl groups include without limitation, methylgroups, ethyl groups, propyl groups, butyl groups, etc. Examples ofbranched alkyls groups include without limitation, t-butyl. Examples ofcyclic alkyl groups include without limitation, cyclopropyl groups,cyclopentyl groups, cyclohexyl groups, etc.

As used herein, the abbreviation “Me” refers to a methyl group; theabbreviation “Et” refers to an ethyl group; the abbreviation “Pr” refersto any propyl group (i.e., n-propyl or isopropyl); the abbreviation“iPr” refers to an isopropyl group; the abbreviation “Bu” refers to anybutyl group (n-butyl, iso-butyl, t-butyl, sec-butyl); the abbreviation“tBu” refers to a tert-butyl group; the abbreviation “sBu” refers to asec-butyl group; the abbreviation “iBu” refers to an iso-butyl group;and the abbreviation “OH” refers to a hydroxyl group.

The standard abbreviations of the elements from the periodic table ofelements are used herein. It should be understood that elements may bereferred to by these abbreviations (e.g., F refers to fluorine, Tirefers to titanium, N refers to nitrogen, etc.).

Please note that several films, such as TiN, are listed throughout thespecification and claims without reference to their properstoichiometry. TiN is TiN_(x)O_(y), wherein x ranges from 0.1 to 2 and yis 0 or 1.

SUMMARY

Methods of removing films from substrates are disclosed. A vapor of ahalide-containing compound is introduced into a chamber containing thesubstrate having the film disposed thereon. Plasma is ignited in thechamber. The chamber is purged. The vapor of a volatile organic compoundis introduced into the chamber. The chamber is purged. The disclosedmethods may include one or more of the following aspects:

-   -   removing native oxide from the film by sputtering with argon        plasma prior to introduction of the vapor of the        halide-containing compound;    -   sputtering the film with argon plasma prior to introduction of        the vapor of the halide-containing compound;    -   further comprising igniting a plasma after introduction of the        vapor of the volatile organic compound;    -   repeating the halide-containing compound introduction, ignition,        purging, volatile organic compound introduction, and purging        steps;    -   wherein performing the halide-containing compound introduction,        ignition, purging, volatile organic compound introduction, and        purging steps one time removes one atomic layer of the film;    -   further comprising repeating the volatile organic compound        introduction and purging steps;    -   the substrate being a silicon-containing substrate;    -   the substrate being a low k layer;    -   the substrate being SiN;    -   the substrate being a metal-containing substrate;    -   the substrate being Co;    -   the substrate being Ni;    -   the film being Si, Ti, Ta, W, Al, Pd, Ir, Co, Fe, B, Cu, Ni, Pt,        Ru, Mn, Mg, Cr, Au, alloys thereof, oxides thereof, nitrides        thereof, or combinations thereof;    -   the film being a sacrificial mask material;    -   the sacrificial mask material being selected from the group        consisting of Ti-containing films, Ta-containing films,        W-containing films, and Al-containing films;    -   the Ti-containing film being Ti;    -   the Ti-containing film being TiN_(x)O_(y), wherein x ranges from        0.1 to 2 and y ranges from 0 to 1;    -   the Ta-containing film being Ta;    -   the sacrificial mask material being TaN_(x)O_(y), wherein x        ranges from 0.1 to 2 and y ranges from 0 to 0.5;    -   the W-containing film being W;    -   the W-containing film being WN_(x)O_(y), wherein x and y each        independently ranges from 0 to 2;    -   the Al-containing film being Al;    -   the Al-containing film being AlCu_(x), wherein x ranges from 0        to 8;    -   the metal layer being an alkaline earth metal layer;    -   the alkaline earth metal layer being a Mg layer;    -   the metal layer being a transition metal layer;    -   the transition metal layer being selected from the group        consisting of Zr, Ta, Cr, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu,        Au, alloy thereof, oxides thereof, nitrides thereof, and        combinations thereof;    -   the transition metal layer being a Zr layer;    -   the transition metal layer being a Ta layer;    -   the transition metal layer being a Cr layer;    -   the transition metal layer being a Mn layer;    -   the transition metal layer being a Fe layer;    -   the transition metal layer being a Ru layer;    -   the transition metal layer being a Co layer;    -   the transition metal layer being a Ir layer;    -   the transition metal layer being a Ni layer;    -   the transition metal layer being a Pd layer;    -   the transition metal layer being a Pt layer;    -   the transition metal layer being a Cu layer;    -   the transition metal layer being a Au layer;    -   the metal layer being a metalloid layer;    -   the metalloid layer being a B layer;    -   the metalloid layer being a Si layer;    -   the halide-containing compound being selected from the group        consisting of Cl₂, HCl, SOCl₂, Br₂, I₂, BCl₃, BBr₃, SO₂Cl₂, FCl,        ClF₃, HBr, HI, F₂, HF, NF₃, POCl₃, CF₄, CHF₃, SF₆, CCl₄, CF₃I,        CF₃Cl, and CF₃Br;    -   the halide-containing compound being Cl₂;    -   the halide-containing compound being HCl;    -   the halide-containing compound being SOCl₂;    -   the halide-containing compound being Br₂;    -   the halide-containing compound being I₂;    -   the halide-containing compound being BCl₃;    -   the halide-containing compound being BBr₃;    -   the halide-containing compound being SO₂Cl₂;    -   the halide-containing compound being FCl;    -   the halide-containing compound being ClF₃;    -   the halide-containing compound being HBr;    -   the halide-containing compound being HI;    -   the halide-containing compound being F₂;    -   the halide-containing compound being HF;    -   the halide-containing compound being NF₃;    -   the halide-containing compound being POCl₃;    -   the halide-containing compound being CF₄;    -   the halide-containing compound being CHF₃;    -   the halide-containing compound being SF₆;    -   the halide-containing compound being CCl₄;    -   the halide-containing compound being CF₃I;    -   the halide-containing compound being CF₃Cl;    -   the halide-containing compound being CF₃Br;    -   the volatile organic compound consisting of the elements C, F,        H, N, O, or combinations thereof;    -   the volatile organic compound being selected from the group        consisting of alcohols, ethers, amines, amidinates, hydrazines,        diketones, carboxylic acids, aldehydes, ketoimines, diketimines,        bis(silyl)amides, and anhydrides;    -   the volatile organic compound being an oxygen-containing        compound;    -   the volatile organic compound being a nitrogen-containing        compound;    -   the volatile organic compound being an alcohol;    -   the alcohol being methanol, ethanol, or isopropanol;    -   the alcohol being ethanol;    -   the volatile organic compound being an ether;    -   the ether being dimethyl ether or diethyl ether;    -   the volatile organic compound being an amine;    -   the amine being methylamine, dimethylamine, ethylamine,        diethylamine, isopropylamine, or diisopropylamine;    -   the volatile organic compound being an amidinate;    -   the volatile organic compound being        N,N′-bis(1-methylethyl)ethanimidamide;    -   the volatile organic compound being a hydrazine;    -   the hydrazine being Me₂NNMe₂ or Et₂NNH₂;    -   the volatile organic compound being a diketone;    -   the diketone being acetyl acetone or hexafluoroacetylacetone;    -   the diketone being acetyl acetone;    -   the volatile organic compound being a carboxylic acid;    -   the carboxylic acid being acetic acid;    -   the volatile organic compound being an aldehyde;    -   the aldehyde being formaldehyde or acetaldehyde;    -   the volatile organic compound being a ketoimines;    -   the ketoimine being 4-ethylamino-pent-3-en-2-one;    -   the volatile organic compound being a diketimine;    -   the diketimine being N,N-diethylpentadiamine;    -   the volatile organic compound being a bis(silyl)amides;    -   the bis(silyl)amide having the formula R₃Si—NH—SiR₃, wherein        each R is independently selected from a C1 to C5 alkyl group;    -   the bis(silyl)amide being bis(trimethylsilyl)amide;    -   the volatile organic compound being an anhydrides; and    -   the anhydride being acetic anhydride.

Methods of removing materials from substrates are disclosed. A vapor ofa halide-containing compound is introduced into a chamber containing thesubstrate having the material disposed thereon. Plasma is ignited in thechamber. The chamber is purged. The vapor of a volatile organic compoundis introduced into the chamber. The chamber is purged. The disclosedmethods may include one or more of the following aspects:

-   -   removing native oxide from the material by sputtering with argon        plasma prior to introduction of the vapor of the        halide-containing compound;    -   sputtering the material with argon plasma prior to introduction        of the vapor of the halide-containing compound;    -   further comprising igniting a plasma after introduction of the        vapor of the volatile organic compound;    -   repeating the halide-containing compound introduction, ignition,        purging, volatile organic compound introduction, and purging        steps;    -   wherein performing the halide-containing compound introduction,        ignition, purging, volatile organic compound introduction, and        purging steps one time removes one atomic layer of the material;    -   further comprising repeating the volatile organic compound        introduction and purging steps;    -   the substrate being a component part of the chamber;    -   the substrate being alumina;    -   the substrate being passivated alumina;    -   the substrate being SiC;    -   the substrate being passivated SiC;    -   the substrate being SiCN;    -   the substrate being passivated SiCN;    -   the substrate being aluminum;    -   the substrate being passivated aluminum;    -   the substrate being quartz;    -   the substrate being passivated quartz;    -   the substrate being ceramic;    -   the substrate being passivated ceramic;    -   the substrate being a Teflon® coating material sold by E.I. Du        Pont de Nemours and Company;    -   the substrate being a passivated Teflon material;    -   the substrate being steel;    -   the substrate being passivated steel;    -   the substrate being a silicon-containing substrate;    -   the substrate being a low k layer;    -   the substrate being SiN;    -   the substrate being a metal-containing substrate;    -   the substrate being Co;    -   the substrate being Ni;    -   the material being Si, Ti, Ta, W, Al, Pd, Ir, Co, Fe, B, Cu, Ni,        Pt, Ru, Mn, Mg, Cr, Au, alloys thereof, oxides thereof, nitrides        thereof, or combinations thereof;    -   The material being a sacrificial mask material;    -   the sacrificial mask material being selected from the group        consisting of Ti-containing films, Ta-containing films,        W-containing films, and Al-containing films;    -   the Ti-containing film being Ti;    -   the Ti-containing film being TiN_(x)O_(y), wherein x ranges from        0.1 to 2 and y ranges from 0 to 1;    -   the Ta-containing film being Ta;    -   the Ta-containing film being TaN_(x)O_(y), wherein x ranges from        0.1 to 2 and y ranges from 0 to 0.5;    -   the W-containing film being W;    -   the W-containing film being WN_(x)O_(y), wherein x and y each        independently ranges from 0 to 2;    -   the Al-containing film being Al;    -   the Al-containing film being AlCu_(x), wherein x ranges from 0        to 8;    -   the metal layer being an alkaline earth metal layer;    -   the alkaline earth metal layer being a Mg layer;    -   the metal layer being a transition metal layer;    -   the transition metal layer being selected from the group        consisting of Zr, Ta, Cr, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu,        Au, alloy thereof, oxides thereof, nitrides thereof, and        combinations thereof;    -   the transition metal layer being a Zr layer;    -   the transition metal layer being a Ta layer;    -   the transition metal layer being a Cr layer;    -   the transition metal layer being a Mn layer;    -   the transition metal layer being a Fe layer;    -   the transition metal layer being a Ru layer;    -   the transition metal layer being a Co layer;    -   the transition metal layer being a Ir layer;    -   the transition metal layer being a Ni layer;    -   the transition metal layer being a Pd layer;    -   the transition metal layer being a Pt layer;    -   the transition metal layer being a Cu layer;    -   the transition metal layer being a Au layer;    -   the metal layer being a metalloid layer;    -   the metalloid layer being a B layer;    -   the metalloid layer being a Si layer;    -   the halide-containing compound being selected from the group        consisting of Cl₂, HCl, SOCl₂, Br₂, I₂, BCl₃, BBr₃, SO₂Cl₂, FCl,        ClF₃, HBr, HI, F₂, HF, NF₃, POCl₃, CF₄, CHF₃, SF₆, CCl₄, CF₃I,        CF₃Cl, and CF₃Br;    -   the halide-containing compound being Cl₂;    -   the halide-containing compound being HCl;    -   the halide-containing compound being SOCl₂;    -   the halide-containing compound being Br₂;    -   the halide-containing compound being I₂;    -   the halide-containing compound being BCl₃;    -   the halide-containing compound being BBr₃;    -   the halide-containing compound being SO₂Cl₂;    -   the halide-containing compound being FCl;    -   the halide-containing compound being ClF₃;    -   the halide-containing compound being HBr;    -   the halide-containing compound being HI;    -   the halide-containing compound being F₂;    -   the halide-containing compound being HF;    -   the halide-containing compound being NF₃;    -   the halide-containing compound being POCl₃;    -   the halide-containing compound being CF₄;    -   the halide-containing compound being CHF₃;    -   the halide-containing compound being SF₆;    -   the halide-containing compound being CCl₄;    -   the halide-containing compound being CF₃I;    -   the halide-containing compound being CF₃Cl;    -   the halide-containing compound being CF₃Br;    -   the volatile organic compound consisting of the elements C, F,        H, N, O, or combinations thereof;    -   the volatile organic compound being selected from the group        consisting of alcohols, ethers, amines, amidinates, hydrazines,        diketones, carboxylic acids, aldehydes, ketoimines, diketimines,        bis(silyl)amides, and anhydrides;    -   the volatile organic compound being an oxygen-containing        compound;    -   the volatile organic compound being a nitrogen-containing        compound;    -   the volatile organic compound being an alcohol;    -   the alcohol being methanol, ethanol, or isopropanol;    -   the alcohol being ethanol;    -   the volatile organic compound being an ether;    -   the ether being dimethyl ether or diethyl ether;    -   the volatile organic compound being an amine;    -   the amine being methylamine, dimethylamine, ethylamine,        diethylamine, isopropylamine, or diisopropylamine;    -   the volatile organic compound being an amidinate;    -   the volatile organic compound being        N,N′-bis(1-methylethyl)ethanimidamide;    -   the volatile organic compound being a hydrazine;    -   the hydrazine being Me₂NNMe₂ or Et₂NNH₂;    -   the volatile organic compound being a diketone;    -   the diketone being acetyl acetone or hexafluoroacetylacetone;    -   the diketone being acetyl acetone;    -   the volatile organic compound being a carboxylic acid;    -   the carboxylic acid being acetic acid;    -   the volatile organic compound being an aldehyde;    -   the aldehyde being formaldehyde or acetaldehyde;    -   the volatile organic compound being a ketoimines;    -   the ketoimine being 4-ethylamino-pent-3-en-2-one;    -   the volatile organic compound being a diketimine;    -   the diketimine being N,N-diethylpentadiamine;    -   the volatile organic compound being a bis(silyl)amides;    -   the bis(silyl)amide having the formula R₃Si—NH—SiR₃, wherein        each R is independently selected from a C1 to C5 alkyl group;    -   the bis(silyl)amide being bis(trimethylsilyl)amide;    -   the volatile organic compound being an anhydrides; and    -   the anhydride being acetic anhydride.

Methods of etching sacrificial mask materials from substrates aredisclosed. A vapor of a halide-containing compound is pulsed into achamber containing the substrate having the sacrificial mask materialdisposed thereon. Plasma is ignited in the chamber during thehalide-containing compound pulse. The vapor of a volatile organiccompound is pulsed into the chamber. The disclosed methods may includeone or more of the following aspects:

-   -   removing native oxide from the sacrificial mask material by        sputtering with argon plasma prior to pulsing of the vapor of        the halide-containing compound;    -   sputtering the sacrificial mask material with argon plasma prior        to pulsing of the vapor of the halide-containing compound;    -   further comprising igniting a plasma during the volatile organic        compound pulse;    -   repeating the halide-containing compound pulse, ignition, and        volatile organic compound pulse steps;    -   further comprising repeating the volatile organic compound pulse        step;    -   wherein performing the halide-containing compound pulse,        ignition, and volatile organic compound pulse steps one time        etches one atomic layer of the sacrificial mask material;    -   the substrate being a silicon-containing substrate;    -   the substrate being a low k layer;    -   the substrate being SiN;    -   the substrate being a metal-containing substrate;    -   the substrate being Co;    -   the substrate being Ni;    -   the sacrificial mask material being selected from the group        consisting of Ti-containing films, Ta-containing films,        W-containing films, and Al-containing films;    -   the Ti-containing film being Ti;    -   the Ti-containing film being TiN_(x)O_(y), wherein x ranges from        0.1 to 2 and y ranges from 0 to 1;    -   the Ta-containing film being Ta;    -   the Ta-containing film being TaN_(x)O_(y), wherein x ranges from        0.1 to 2 and y ranges from 0 to 0.5;    -   the W-containing film being W;    -   the W-containing film being WN_(x)O_(y), wherein x and y each        independently ranges from 0 to 2;    -   the Al-containing film being Al;    -   the Al-containing film being AlCu_(x), wherein x ranges from 0        to 8;    -   the halide-containing compound being selected from the group        consisting of Cl₂, HCl, SOCl₂, Br₂, I₂, BCl₃, BBr₃, SO₂Cl₂, FCl,        ClF₃, HBr, HI, F₂, HF, NF₃, POCl₃, CF₄, CHF₃, SF₆, CCl₄, CF₃I,        CF₃Cl, and CF₃Br;    -   the halide-containing compound being Cl₂;    -   the halide-containing compound being HCl;    -   the halide-containing compound being SOCl₂;    -   the halide-containing compound being Br₂;    -   the halide-containing compound being I₂;    -   the halide-containing compound being BCl₃;    -   the halide-containing compound being BBr₃;    -   the halide-containing compound being SO₂Cl₂;    -   the halide-containing compound being FCl;    -   the halide-containing compound being ClF₃;    -   the halide-containing compound being HBr;    -   the halide-containing compound being HI;    -   the halide-containing compound being F₂;    -   the halide-containing compound being HF;    -   the halide-containing compound being NF₃;    -   the halide-containing compound being POCl₃;    -   the halide-containing compound being CF₄;    -   the halide-containing compound being CHF₃;    -   the halide-containing compound being SF₆;    -   the halide-containing compound being CCl₄;    -   the halide-containing compound being CF₃I;    -   the halide-containing compound being CF₃Cl;    -   the halide-containing compound being CF₃Br;    -   the volatile organic compound consisting of the elements C, F,        H, N, O, or combinations thereof;    -   the volatile organic compound being selected from the group        consisting of alcohols, ethers, amines, amidinates, hydrazines,        diketones, carboxylic acids, aldehydes, ketoimines, diketimines,        bis(silyl)amides, and anhydrides;    -   the volatile organic compound being an oxygen-containing        compound;    -   the volatile organic compound being a nitrogen-containing        compound;    -   the volatile organic compound being an alcohol;    -   the alcohol being methanol, ethanol, or isopropanol;    -   the alcohol being ethanol;    -   the volatile organic compound being an ether;    -   the ether being dimethyl ether or diethyl ether;    -   the volatile organic compound being an amine;    -   the amine being methylamine, dimethylamine, ethylamine,        diethylamine, isopropylamine, or diisopropylamine;    -   the volatile organic compound being an amidinate;    -   the volatile organic compound being        N,N′-bis(1-methylethyl)ethanimidamide;    -   the volatile organic compound being a hydrazine;    -   the hydrazine being Me₂NNMe₂ or Et₂NNH₂;    -   the volatile organic compound being a diketone;    -   the diketone being acetyl acetone or hexafluoroacetylacetone;    -   the diketone being acetyl acetone;    -   the volatile organic compound being a carboxylic acid;    -   the carboxylic acid being acetic acid;    -   the volatile organic compound being an aldehyde;    -   the aldehyde being formaldehyde or acetaldehyde;    -   the volatile organic compound being a ketoimines;    -   the ketoimine being 4-ethylamino-pent-3-en-2-one;    -   the volatile organic compound being a diketimine;    -   the diketimine being N,N-diethylpentadiamine;    -   the volatile organic compound being a bis(silyl)amides;    -   the bis(silyl)amide having the formula R₃Si—NH—SiR₃, wherein        each R is independently selected from a C1 to C5 alkyl group;    -   the bis(silyl)amide being bis(trimethylsilyl)amide;    -   the volatile organic compound being an anhydrides; and    -   the anhydride being acetic anhydride.

Methods of etching metal layers from substrates are disclosed. A vaporof a halide-containing compound is pulsed into a chamber containing thesubstrate having the layer disposed thereon. Plasma is ignited in thechamber during the halide-containing compound pulse. The vapor of avolatile organic compound is pulsed into the chamber. The disclosedmethods may include one or more of the following aspects:

-   -   removing native oxide from the metal layer by sputtering with        argon plasma prior to pulsing of the vapor of the        halide-containing compound;    -   sputtering the metal layer with argon plasma prior to pulsing of        the vapor of the halide-containing compound;    -   further comprising igniting a plasma during the volatile organic        compound pulse;    -   repeating the halide-containing compound pulse, ignition, and        volatile organic compound pulse steps;    -   further comprising repeating the volatile organic compound pulse        step;    -   wherein performing the halide-containing compound pulse,        ignition, and volatile organic compound pulse steps one time        etches one atomic layer of the metal layer;    -   the substrate being a component part of the chamber;    -   the substrate being alumina;    -   the substrate being passivated alumina;    -   the substrate being SiC;    -   the substrate being passivated SiC;    -   the substrate being SiCN;    -   the substrate being passivated SiCN;    -   the substrate being aluminum;    -   the substrate being passivated aluminum;    -   the substrate being quartz;    -   the substrate being passivated quartz;    -   the substrate being ceramic;    -   the substrate being passivated ceramic;    -   the substrate being a Teflon material;    -   the substrate being a passivated Teflon material;    -   the substrate being steel;    -   the substrate being passivated steel;    -   the substrate being a silicon-containing substrate;    -   the substrate being a low k layer;    -   the substrate being SiN;    -   the substrate being a metal-containing substrate;    -   the substrate being Co;    -   the substrate being Ni;    -   the metal layer being an alkaline earth metal layer;    -   the alkaline earth metal layer being a Mg layer;    -   the metal layer being a transition metal layer;    -   the transition metal layer being selected from the group        consisting of Zr, Ta, Cr, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu,        Au, alloy thereof, oxides thereof, nitrides thereof, and        combinations thereof;    -   the transition metal layer being a Zr layer;    -   the transition metal layer being a Ta layer;    -   the transition metal layer being a Cr layer;    -   the transition metal layer being a Mn layer;    -   the transition metal layer being a Fe layer;    -   the transition metal layer being a Ru layer;    -   the transition metal layer being a Co layer;    -   the transition metal layer being a Ir layer;    -   the transition metal layer being a Ni layer;    -   the transition metal layer being a Pd layer;    -   the transition metal layer being a Pt layer;    -   the transition metal layer being a Cu layer;    -   the transition metal layer being a Au layer;    -   the metal layer being a metalloid layer;    -   the metalloid layer being a B layer;    -   the metalloid layer being a Si layer;    -   the halide-containing compound being selected from the group        consisting of Cl₂, HCl, SOCl₂, Br₂, I₂, BCl₃, BBr₃, SO₂Cl₂, FCl,        ClF₃, HBr, HI, F₂, HF, NF₃, POCl₃, CF₄, CHF₃, SF₆, CCl₄, CF₃I,        CF₃Cl, and CF₃Br;    -   the halide-containing compound being Cl₂;    -   the halide-containing compound being HCl;    -   the halide-containing compound being SOCl₂;    -   the halide-containing compound being Br₂;    -   the halide-containing compound being I₂;    -   the halide-containing compound being BCl₃;    -   the halide-containing compound being BBr₃;    -   the halide-containing compound being SO₂Cl₂;    -   the halide-containing compound being FCl;    -   the halide-containing compound being ClF₃;    -   the halide-containing compound being HBr;    -   the halide-containing compound being HI;    -   the halide-containing compound being F₂;    -   the halide-containing compound being HF;    -   the halide-containing compound being NF₃;    -   the halide-containing compound being POCl₃;    -   the halide-containing compound being CF₄;    -   the halide-containing compound being CHF₃;    -   the halide-containing compound being SF₆;    -   the halide-containing compound being CCl₄;    -   the halide-containing compound being CF₃I;    -   the halide-containing compound being CF₃Cl;    -   the halide-containing compound being CF₃Br;    -   the volatile organic compound consisting of the elements C, F,        H, N, O, or combinations thereof;    -   the volatile organic compound being selected from the group        consisting of alcohols, ethers, amines, amidinates, hydrazines,        diketones, carboxylic acids, aldehydes, ketoimines, diketimines,        bis(silyl)amides, and anhydrides;    -   the volatile organic compound being an oxygen-containing        compound;    -   the volatile organic compound being a nitrogen-containing        compound;    -   the volatile organic compound being an alcohol;    -   the alcohol being methanol, ethanol, or isopropanol;    -   the alcohol being ethanol;    -   the volatile organic compound being an ether;    -   the ether being dimethyl ether or diethyl ether;    -   the volatile organic compound being an amine;    -   the amine being methylamine, dimethylamine, ethylamine,        diethylamine, isopropylamine, or diisopropylamine;    -   the volatile organic compound being an amidinate;    -   the volatile organic compound being        N,N′-bis(1-methylethyl)ethanimidamide;    -   the volatile organic compound being a hydrazine;    -   the hydrazine being Me₂NNMe₂ or Et₂NNH₂;    -   the volatile organic compound being a diketone;    -   the diketone being acetyl acetone or hexafluoroacetylacetone;    -   the diketone being acetyl acetone;    -   the volatile organic compound being a carboxylic acid;    -   the carboxylic acid being acetic acid;    -   the volatile organic compound being an aldehyde;    -   the aldehyde being formaldehyde or acetaldehyde;    -   the volatile organic compound being a ketoimines;    -   the ketoimine being 4-ethylamino-pent-3-en-2-one;    -   the volatile organic compound being a diketimine;    -   the diketimine being N,N-diethylpentadiamine;    -   the volatile organic compound being a bis(silyl)amides;    -   the bis(silyl)amide having the formula R₃Si—NH—SiR₃, wherein        each R is independently selected from a C1 to C5 alkyl group;    -   the bis(silyl)amide being bis(trimethylsilyl)amide;    -   the volatile organic compound being an anhydrides; and    -   the anhydride being acetic anhydride.

Methods of selectively etching films from substrates are disclosed. Avapor of a halide-containing compound is pulsed into a chambercontaining the substrate having the film disposed thereon. Plasma isignited in the chamber during the halide-containing compound pulse. Thevapor of a volatile organic compound is pulsed into the chamber. Thedisclosed methods may include one or more of the following aspects:

-   -   removing native oxide from the film by sputtering with argon        plasma prior to pulsing of the vapor of the halide-containing        compound;    -   sputtering the film with argon plasma prior to pulsing of the        vapor of the halide-containing compound;    -   further comprising igniting a plasma during the volatile organic        compound pulse;    -   repeating the halide-containing compound pulse, ignition, and        volatile organic compound pulse steps;    -   further comprising repeating the volatile organic compound pulse        step;    -   wherein performing the halide-containing compound pulse,        ignition, and volatile organic compound pulse steps one time        etches one atomic layer of the film;    -   the substrate being a silicon-containing substrate;    -   the substrate being a low k layer;    -   the substrate being SiN;    -   the substrate being a metal-containing substrate;    -   the substrate being Co;    -   the substrate being Ni;    -   the film being selected from the group consisting of        Ti-containing films,    -   Ta-containing films, W-containing films, and Al-containing        films; the Ti-containing film being Ti;    -   the Ti-containing film being TiN_(x)O_(y), wherein x ranges from        0.1 to 2 and y ranges from 0 to 1;    -   the Ta-containing film being Ta;    -   the film being TaN_(x)O_(y), wherein x ranges from 0.1 to 2 and        y ranges from 0 to 0.5;    -   the W-containing film being W;    -   the W-containing film being WN_(x)O_(y), wherein x and y each        independently ranges from 0 to 2;    -   the Al-containing film being Al;    -   the Al-containing film being AlCu_(x), wherein x ranges from 0        to 8;    -   the film being an alkaline earth metal layer;    -   the alkaline earth metal layer being a Mg layer;    -   the film being a transition metal layer;    -   the transition metal layer being selected from the group        consisting of Zr, Ta, Cr, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu,        Au, alloy thereof, oxides thereof, nitrides thereof, and        combinations thereof;    -   the transition metal layer being a Zr layer;    -   the transition metal layer being a Ta layer;    -   the transition metal layer being a Cr layer;    -   the transition metal layer being a Mn layer;    -   the transition metal layer being a Fe layer;    -   the transition metal layer being a Ru layer;    -   the transition metal layer being a Co layer;    -   the transition metal layer being a Ir layer;    -   the transition metal layer being a Ni layer;    -   the transition metal layer being a Pd layer;    -   the transition metal layer being a Pt layer;    -   the transition metal layer being a Cu layer;    -   the transition metal layer being a Au layer;    -   the film being a metalloid layer;    -   the metalloid layer being a B layer;    -   the metalloid layer being a Si layer;    -   the halide-containing compound being selected from the group        consisting of Cl₂, HCl, SOCl₂, Br₂, I₂, BCl₃, BBr₃, SO₂Cl₂, FCl,        ClF₃, HBr, HI, F₂, HF, NF₃, POCl₃, CF₄, CHF₃, SF₆, CCl₄, CF₃I,        CF₃Cl, and CF₃Br;    -   the halide-containing compound being Cl₂;    -   the halide-containing compound being HCl;    -   the halide-containing compound being SOCl₂;    -   the halide-containing compound being Br₂;    -   the halide-containing compound being I₂;    -   the halide-containing compound being BCl₃;    -   the halide-containing compound being BBr₃;    -   the halide-containing compound being SO₂Cl₂;    -   the halide-containing compound being FCl;    -   the halide-containing compound being ClF₃;    -   the halide-containing compound being HBr;    -   the halide-containing compound being HI;    -   the halide-containing compound being F₂;    -   the halide-containing compound being HF;    -   the halide-containing compound being NF₃;    -   the halide-containing compound being POCl₃;    -   the halide-containing compound being CF₄;    -   the halide-containing compound being CHF₃;    -   the halide-containing compound being SF₆;    -   the halide-containing compound being CCl₄;    -   the halide-containing compound being CF₃I;    -   the halide-containing compound being CF₃Cl;    -   the halide-containing compound being CF₃Br;    -   the volatile organic compound consisting of the elements C, F,        H, N, O, or combinations thereof;    -   the volatile organic compound being selected from the group        consisting of alcohols, ethers, amines, amidinates, hydrazines,        diketones, carboxylic acids, aldehydes, ketoimines, diketimines,        bis(silyl)amides, and anhydrides;    -   the volatile organic compound being an oxygen-containing        compound;    -   the volatile organic compound being a nitrogen-containing        compound;    -   the volatile organic compound being an alcohol;    -   the alcohol being methanol, ethanol, or isopropanol;    -   the alcohol being ethanol;    -   the volatile organic compound being an ether;    -   the ether being dimethyl ether or diethyl ether;    -   the volatile organic compound being an amine;    -   the amine being methylamine, dimethylamine, ethylamine,        diethylamine, isopropylamine, or diisopropylamine;    -   the volatile organic compound being an amidinate;    -   the volatile organic compound being        N,N′-bis(1-methylethyl)ethanimidamide;    -   the volatile organic compound being a hydrazine;    -   the hydrazine being Me₂NNMe₂ or Et₂NNH₂;    -   the volatile organic compound being a diketone;    -   the diketone being acetyl acetone or hexafluoroacetylacetone;    -   the diketone being acetyl acetone;    -   the volatile organic compound being a carboxylic acid;    -   the carboxylic acid being acetic acid;    -   the volatile organic compound being an aldehyde;    -   the aldehyde being formaldehyde or acetaldehyde;    -   the volatile organic compound being a ketoimines;    -   the ketoimine being 4-ethylamino-pent-3-en-2-one;    -   the volatile organic compound being a diketimine;    -   the diketimine being N,N-diethylpentadiamine;    -   the volatile organic compound being a bis(silyl)amides;    -   the bis(silyl)amide having the formula R₃Si—NH—SiR₃, wherein        each R is independently selected from a C1 to C5 alkyl group;    -   the bis(silyl)amide being bis(trimethylsilyl)amide;    -   the volatile organic compound being an anhydrides; and    -   the anhydride being acetic anhydride.

Methods of removing films from substrates are disclosed. The substrateis sputtered with argon plasma. The vapor of a volatile organic compoundis introduced into the chamber. The chamber is purged. The disclosedmethods may include one or more of the following aspects:

-   -   further comprising igniting a plasma during the volatile organic        compound introduction step;    -   repeating the sputtering, volatile organic compound        introduction, and purging steps;    -   repeating the volatile organic compound introduction and purging        steps;    -   wherein performing the sputtering, volatile organic compound        introduction, and purging steps one time removes one atomic        layer of the film;    -   the substrate being a silicon-containing substrate;    -   the substrate being a low k layer;    -   the substrate being SiN;    -   the substrate being a metal-containing substrate;    -   the substrate being Co;    -   the substrate being Ni;    -   the film being selected from the group consisting of        Ti-containing films, Ta-containing films, W-containing films,        and Al-containing films;    -   the Ti-containing film being Ti;    -   the Ti-containing film being TiN_(x)O_(y), wherein x ranges from        0.1 to 2 and y ranges from 0 to 1;    -   the Ta-containing film being Ta;    -   the film being TaN_(x)O_(y), wherein x ranges from 0.1 to 2 and        y ranges from 0 to 0.5;    -   the W-containing film being W;    -   the W-containing film being WN_(x)O_(y), wherein x and y each        independently ranges from 0 to 2;    -   the Al-containing film being Al;    -   the Al-containing film being AlCu_(x), wherein x ranges from 0        to 8;    -   the film being an alkaline earth metal layer;    -   the alkaline earth metal layer being a Mg layer;    -   the film being a transition metal layer;    -   the transition metal layer being selected from the group        consisting of Zr, Ta,    -   Cr, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu, Au, alloy thereof,        oxides thereof, nitrides thereof, and combinations thereof;    -   the transition metal layer being a Zr layer;    -   the transition metal layer being a Ta layer;    -   the transition metal layer being a Cr layer;    -   the transition metal layer being a Mn layer;    -   the transition metal layer being a Fe layer;    -   the transition metal layer being a Ru layer;    -   the transition metal layer being a Co layer;    -   the transition metal layer being a Ir layer;    -   the transition metal layer being a Ni layer;    -   the transition metal layer being a Pd layer;    -   the transition metal layer being a Pt layer;    -   the transition metal layer being a Cu layer;    -   the transition metal layer being a Au layer;    -   the film being a metalloid layer;    -   the metalloid layer being a B layer;    -   the metalloid layer being a Si layer;    -   the halide-containing compound being selected from the group        consisting of Cl₂, HCl, SOCl₂, Br₂, I₂, BCl₃, BBr₃, SO₂Cl₂, FCl,        ClF₃, HBr, HI, F₂, HF, NF₃, POCl₃, CF₄, CHF₃, SF₆, CCl₄, CF₃I,        CF₃Cl, and CF₃Br;    -   the halide-containing compound being Cl₂;    -   the halide-containing compound being HCl;    -   the halide-containing compound being SOCl₂;    -   the halide-containing compound being Br₂;    -   the halide-containing compound being I₂;    -   the halide-containing compound being BCl₃;    -   the halide-containing compound being BBr₃;    -   the halide-containing compound being SO₂Cl₂;    -   the halide-containing compound being FCl;    -   the halide-containing compound being ClF₃;    -   the halide-containing compound being HBr;    -   the halide-containing compound being HI;    -   the halide-containing compound being F₂;    -   the halide-containing compound being HF;    -   the halide-containing compound being NF₃;    -   the halide-containing compound being POCl₃;    -   the halide-containing compound being CF₄;    -   the halide-containing compound being CHF₃;    -   the halide-containing compound being SF₆;    -   the halide-containing compound being CCl₄;    -   the halide-containing compound being CF₃I;    -   the halide-containing compound being CF₃Cl;    -   the halide-containing compound being CF₃Br;    -   the volatile organic compound consisting of the elements C, F,        H, N, O, or combinations thereof;    -   the volatile organic compound being selected from the group        consisting of alcohols, ethers, amines, amidinates, hydrazines,        diketones, carboxylic acids, aldehydes, ketoimines, diketimines,        bis(silyl)amides, and anhydrides;    -   the volatile organic compound being an alcohol;    -   the alcohol being methanol, ethanol, or isopropanol;    -   the alcohol being ethanol;    -   the volatile organic compound being an ether;    -   the ether being dimethyl ether or diethyl ether;    -   the volatile organic compound being an amine;    -   the amine being methylamine, dimethylamine, ethylamine,        diethylamine, isopropylamine, or diisopropylamine;    -   the volatile organic compound being an amidinate;    -   the volatile organic compound being        N,N′-bis(1-methylethyl)ethanimidamide;    -   the volatile organic compound being a hydrazine;    -   the hydrazine being Me₂NNMe₂ or Et₂NNH₂;    -   the volatile organic compound being a diketone;    -   the diketone being acetyl acetone or hexafluoroacetylacetone;    -   the diketone being acetyl acetone;    -   the volatile organic compound being a carboxylic acid;    -   the carboxylic acid being acetic acid;    -   the volatile organic compound being an aldehyde;    -   the aldehyde being formaldehyde or acetaldehyde;    -   the volatile organic compound being a ketoimines;    -   the ketoimine being 4-ethylamino-pent-3-en-2-one;    -   the volatile organic compound being a diketimine;    -   the diketimine being N,N-diethylpentadiamine;    -   the volatile organic compound being a bis(silyl)amides;    -   the bis(silyl)amide having the formula R₃Si—NH—SiR₃, wherein        each R is independently selected from a C1 to C5 alkyl group;    -   the bis(silyl)amide being bis(trimethylsilyl)amide;    -   the volatile organic compound being an anhydrides; and    -   the anhydride being acetic anhydride.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature and objects of the presentinvention, reference should be made to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like elements are given the same or analogous reference numbersand wherein:

FIG. 1 is a schematic diagram of the atomic layer etch process disclosedherein;

FIG. 2 a is a diagram showing exemplary layers in a MRAM stack;

FIG. 2 b is a diagram showing exemplary layers in an alternate MRAMstack;

FIG. 2 c is a diagram showing exemplary layers used in patterning inback end of the line (BEOL);

FIG. 3 is a diagram of the experimental chamber used to perform thetesting disclosed in the examples.

FIG. 4 is a spectrum obtained by energy dispersive x-ray spectroscopy(EDS) of a 8 mm×8 mm Si substrate containing a TiN layer thereon beforeetching;

FIG. 5 is a spectrum obtained by EDS of the sample located on the gasshowerhead 105 of the chamber 100 of FIG. 3 (the “top sample T”) afterexposure to Cl₂, no plasma;

FIG. 6 is a spectrum obtained by EDS of the sample located on thethermally conductive aluminum plate 110 of the chamber 100 of FIG. 3(the “bottom sample B”) after exposure to Cl₂, no plasma.

FIG. 7 is a scanning electron microscope photograph of a TiN film takenafter 300 seconds of etching with plasma Ar and CF₄;

FIG. 8 is a spectrum obtained by EDS of the top sample T after exposureto 100 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 9 is a spectrum obtained by EDS of the bottom sample B afterexposure to 100 cycles of Cl₂ with plasma followed by ethanol withplasma;

FIG. 10 is a spectrum obtained by EDS of the bottom sample B afterexposure to 10 cycles of Cl₂ with plasma followed by ethanol withplasma;

FIG. 11 is a spectrum obtained by EDS of the bottom sample B afterexposure to 20 cycles of Cl₂ with plasma followed by ethanol withplasma;

FIG. 12 is a spectrum obtained by EDS of the bottom sample B afterexposure to 30 cycles of Cl₂ with plasma followed by ethanol withplasma;

FIG. 13 is a spectrum obtained by EDS of the bottom sample B afterexposure to 40 cycles of Cl₂ with plasma followed by ethanol withplasma;

FIG. 14 is a spectrum obtained by EDS of the bottom sample B afterexposure to 50 cycles of Cl₂ with plasma followed by ethanol withplasma;

FIG. 15 is a graph comparing the TiN layer thickness in nm after theetch processes of Comparative Example 2 and 4 and Example 2;

FIG. 16 is a spectrum obtained by EDS of a 8 mm×8 mm Si substratecontaining an approximately 15 nm Ti layer and an approximately 100 nmFe layer thereon (the “Fe sample”) before etching;

FIG. 17 is a spectrum obtained by EDS of the Fe sample after exposure to15 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 18 is a spectrum obtained by EDS of the Fe sample after exposure to30 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 19 is a spectrum obtained by EDS of the Fe sample after exposure to45 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 20 is a spectrum obtained by EDS of the Fe sample after exposure to74 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 21 is a spectrum obtained by EDS of a comparative Fe sample subjectto 100 cycles of plasma Cl₂;

FIG. 22 is a spectrum obtained by EDS of the Pd layer before etching;

FIG. 23 is a spectrum obtained by EDS of the Pd sample after exposure to15 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 24 is a spectrum obtained by EDS of the Pd sample after exposure to30 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 25 is a spectrum obtained by EDS of the Pd sample after exposure to45 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 26 is a spectrum obtained by EDS of the Pd sample after exposure to74 cycles of Cl₂ with plasma followed by ethanol with plasma;

FIG. 27 is a spectrum obtained by EDS of a comparative Pd sample subjectto 100 cycles of plasma Cl₂;

FIG. 28 is a graph comparing the Pd etch rate (nm/cycle) from a cyclicCl₂ etch process, a cyclic acetylacetonate etch process, and a cyclicetch process using both Cl₂ and acetylacetonate;

FIG. 29 is a diagram of the modified experimental chamber used inComparative Examples 6 and 7 and Example 4;

FIG. 30 is a graph comparing the etch rate (nm/cycle) of Co, Fe, Ni, andPd using cyclic Cl₂ and varying power (0, 100, and 200 W) at 240° C.;

FIG. 31 is a graph comparing the etch rate (nm/cycle) of Co, Fe, Ni, andPd using cyclic Cl₂ and varying power (0, 100, and 200 W) at 100° C.;and

FIG. 32 is a graph comparing the etch rate (nm/cycle) of Co, Fe, Ni, andPd using cyclic aceylacetonate at 25 cycles vs. 100 cycles.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Methods of removing a layer from a substrate are disclosed. Moreparticularly, methods of removing sacrificial mask materials fromsubstrates are disclosed. Alternatively, methods of removing metallayers from substrates are disclosed. The metal layer or sacrificialmask material is etched or selectively etched from a substrate. Themetal layer or sacrificial mask material may also be removed from thechamber walls or other surfaces in the chamber.

As illustrated in FIG. 1, the disclosed methods remove the layer byrepetition of a cycle of pulsing a plasma containing a halide-containingcompound (Plasma Reactant A) over the layer followed by pulsing avolatile organic compound (Reactant B) over the layer. A plasma may ormay not be ignited for the volatile organic compound pulse. One ofordinary skill in the art will recognize that either thehalide-containing compound pulse or the volatile organic compound pulsemay start the cycle without departing from the teachings herein.Applicants believe that one cycle may remove one atomic layer (i.e.,atomic layer etching) of the layer when the process parameters areoptimized. Sufficient repetition of the cycles removes the entire layer.

Suitable layers may include sacrificial mask materials or metal layers.Exemplary sacrificial mask materials include Ti-, Ta-, W-, orAl-containing layers. Exemplary metal layers include Pd, Ir, Co, Fe, B,Cu, Ni, Pt, Ru, Mn, Mg, Cr, Au, alloys thereof, oxides thereof, nitridesthereof, and combinations thereof. The sacrificial mask material may beused to form a patterning layer. The metal layer may be used to form aMRAM device stack.

The mask material may be any Ti-containing films, Ta-containing films,W-containing films, or Al-containing films. These layers are currentlyused as hard marks, although other functions are not excluded from thescope of this application. Exemplary Ti-containing films include Ti orTiN_(x)O_(y), wherein x ranges from 0.1 to 2 and y ranges from 0 to 1.Exemplary Ta-containing films include Ta or TaN_(x)O_(y), wherein xranges from 0.1 to 2 and y ranges from 0 to 0.5. Exemplary W-containingfilms include W or WN_(x)O_(y), wherein x and y each independentlyranges from 0 to 2. Exemplary Al-containing films include Al orAlCu_(x), wherein x ranges from 0 to 8. The layer or mask material maybe sputter cleaned with Ar plasma to remove native oxide from the toplayer at the beginning of the process.

The layer may serve as a sacrificial mask layer to permit patterning ofother layers on the substrate. As a result, the layer is resistant tothe chemicals used to etch the other layers on the substrate. After thepatterning is complete, removal of the sacrificial mask layer may benecessary. However, removal of the layer may be difficult because of itschemical resistant properties. Typically, removal of the mask layer hasrequired use of liquid phase solvents, which can damage the remainingstructures on the substrate, for example by creating sticktion force insmall trenches that distort structures. One of ordinary skill in the artwill recognize that the chemically resistant layer may also form on thereactor walls. As a result, the methods disclosed herein are not limitedto removal of layers from semiconductor wafers, and instead may also beused to remove layers from chamber walls.

FIGS. 2 a-2 c provide three alternate diagrams showing exemplary layersin a MRAM stack. One of ordinary skill in the art will recognize thatthe MRAM stack may contain additional or fewer layers depending on theMRAM cell desired. The photoresist mask layer of FIG. 2 a-2 c may be anyof the mask layers discussed above. As shown in FIG. 2 c, thephotoresist mask layer may be a titanium containing hard mask. The topand bottom contact (FIG. 2 a) or electrode (FIG. 2 b) layers may be Au,Cr, Cu, Ti, Ta, Ru, or combinations thereof. The top and bottom magnetof FIG. 2 a may be B, Co, Fe, Ni, and combinations thereof. The tunnelbarrier layer of FIGS. 2 a and 2 b may be AlO, Cu or MgO. The substrateof FIGS. 2 a-2 c may be Si. The cap layer of FIG. 2 b may be PtMn, AlO,MgO, Ru, Ta, or TaN. The free layer and top and bottom pinned layers ofFIG. 2 b may be ferromagnetic metals, such as CoFeB or NiFe. Ru forms anon-magnetic spacer layer in FIG. 2 b. The antiferromagnetic layer ofFIG. 2 b may be PtMn or IrMn. The seed layer of FIG. 2 b may be NiFe,NiFeCu, or Cu. The patterned region of FIG. 2 b may be thephosphosilicate glass layer containing tungsten, copper, or other metalcontacts used in the transistor region. The low k layer of FIG. 2 c maybe any silicon containing low k layer, such as SiO₂, SiCOH, etc. Theetch stop layer of FIG. 2 c may be SiC or SiN. The patterned region ofFIG. 2 c may be the phosphosilicate glass layer containing tungsten,copper, or other metal contacts used in the front end of the line (FEOL)or middle of the line (MOL) transistor region. Alternatively, thepatterned region of FIG. 2 c may be the low k layer containing coppercontacts used in the back end of the line (BEOL) interconnect region.The multiple layers that form MRAM materials are difficult to etch. Thedisclosed processes provide the capability to select the properhalide-containing compound and/or volatile organic compound tosequentially remove one atomic layer of each metal layer in the MRAMstack. Applicants believe that the proposed cyclic etching processes mayserve as a “reverse ALD” technique. In other words, the proposed cyclicetching process may be able to re-generate the volatile precursor thathad originally been used to deposit the metal layer and easily remove itfrom the etch chamber.

The vapor of a halide-containing compound is introduced into a chambercontaining the substrate having the layer disposed thereon. Thehalide-containing compound may be Cl₂, HCl, SOCl₂, Br₂, I₂, BCl₃, BBr₃,SO₂Cl₂, FCl, ClF₃, HBr, HI, F₂, HF, NF₃, POCl₃, CF₄, CHF₃, SF₆, CCl₄,CF₃I, CF₃Cl, CF₃Br and combinations thereof. These halide-containingcompounds are either commercially available or may be synthesized bymethods known in the art.

In order to prevent surface changes on the substrate or any otherprocess inconsistencies, purity of the halide-containing compound isbetween approximately 99.99% v/v and 100% v/v, preferably 99.999% v/vand 100% v/v. The concentration of O₂ in the halide-containing compoundis preferably between approximately 0 ppmv and approximately 50 ppmv,preferably between approximately 0 ppmv and approximately 4 ppmv, andmore preferably between approximately 0 ppmv and approximately 1 ppmv.The concentration of H₂O in the halide-containing compound is preferablybetween approximately 0 ppmv and approximately 10 ppmv, preferablybetween approximately 0 ppmv and approximately 2 ppmv, and morepreferably between approximately 0 ppmv and approximately 1 ppmv.

The chamber may be any enclosure or chamber within a device in whichplasma etching methods take place such as, and without limitation,Reactive Ion Etching (RIE), Dual Capacitively Coupled Plasma (CCP) withsingle or multiple frequency RF sources, Inductively Coupled Plasma(ICP), or Microwave Plasma reactors, or other types of etching systemscapable of selectively removing a portion of the layer by generatingactive species. The plasma may be generated or present within thereactor itself. Alternatively, the plasma may generally be at a locationremoved from the reactor, for instance, in a remotely located plasmasystem. One of skill in the art will recognize the different plasmareaction chamber designs provide different electron temperature control.Suitable commercially available plasma reaction chambers include but arenot limited to the Applied Materials magnetically enhanced reactive ionetcher sold under the trademark eMAX™ or the Lam Research Dual CCPreactive ion etcher Dielectric etch product family sold under thetrademark 2300® Flex™.

The plasma reaction chamber may contain one or more than one substrate.For example, the substrate may be any component part of the plasmareaction chamber, such as passivated or non-passivated alumina,aluminum, ceramic, quartz, steel, SiC, SiN, SiCN, or Teflon® coatingmaterial sold by E.I. Du Pont de Nemours and Company. Alternatively, theplasma reaction chamber may contain from 1 to 200 silicon wafers havingfrom 25.4 mm to 450 mm diameters. The one or more substrates may be anysuitable substrate used in semiconductor, photovoltaic, flat panel orLCD-TFT device manufacturing. As discussed above with regards to FIGS. 2a-2 c, the substrate may have multiple films or layers thereon,including one or more silicon-containing films or layers. The substratemay or may not be patterned. Examples of suitable layers include withoutlimitation silicon (such as amorphous silicon, polysilicon, crystallinesilicon, any of which may further be p-doped or n-doped with B, C, P,As, and/or Ge), silica, silicon nitride, silicon oxide, siliconoxynitride, tungsten, titanium nitride, tantalum nitride, mask materialssuch as amorphous carbon, antireflective coatings, photoresistmaterials, or combinations thereof. The silicon oxide layer may form adielectric material, such as an organic based or silicon oxide basedlow-k dielectric material (e.g., a porous SiCOH film). An exemplarylow-k dielectric material is sold by Applied Materials under the tradename Black Diamond II or III. Additionally, layers comprising tungstenor noble metals (e.g. platinum, palladium, rhodium or gold) may be used.

The substrate temperature of the chamber may range from approximately−50° C. to approximately 400° C., preferably from approximately 25° C.to approximately 250° C. The chamber wall may be hot or cold (i.e., fromapproximately 25° C. to approximately 400° C.). The pressure of thechamber may range from approximately 1 mTorr to atmospheric pressure(760 Torr), preferably from approximately 1 mTorr to 15 Torr.

The halide-containing compounds may be in gas, liquid, or solid form atstandard temperature and pressure. As the term “gas” is synonymous withthe term “vapor,” the gas compounds may be directly introduced into thechamber.

If in liquid form, the halide-containing compound may be supplied eitherin neat form or in a blend with a suitable solvent, such as ethylbenzene, xylene, mesitylene, decane, dodecane. The halide-containingliquids may be present in varying concentrations in the solvent. One ormore of the neat or blended halide-containing liquids are introducedinto a reactor in vapor form by conventional means, such as tubingand/or flow meters. The vapor form of the halide-containing liquid maybe produced by vaporizing the neat or blended compound solution througha conventional vaporization step such as direct vaporization,distillation, or by bubbling. The neat or blended liquid may be fed inliquid state to a vaporizer where it is vaporized before it isintroduced into the reactor. Alternatively, the neat or blended liquidmay be vaporized by passing a carrier gas into a container containingthe compound or by bubbling the carrier gas into the compound. Thecarrier gas may include, but is not limited to, Ar, He, N₂, and mixturesthereof. Bubbling with a carrier gas may also help remove any dissolvedoxygen present in the neat or blended compound solution. The carrier gasand halide-containing compound are then introduced into the reactor as avapor.

The vapour of a solid halide-containing compound may be supplied using asublimator, such as the one disclosed in PCT Publication WO2009/087609to Xu et al. Alternatively, the solid halide-containing compound may beblended with a suitable solvent, such as ethyl benzene, xylene,mesitylene, decalin, decane, dodecane. The halide-containing compoundmay be present in varying concentrations in the solvent.

If necessary, the container of the halide-containing compound may beheated to a temperature that permits the compound to have sufficientvapor pressure in its gas, liquid, or solid phase. The container may bemaintained at temperatures in the range of, for example, approximately0° C. to approximately 150° C. Those skilled in the art recognize thatthe temperature of the container may be adjusted in a known manner tocontrol the amount of compound vaporized.

The vapor of the halide-containing compound is introduced into theplasma reaction chamber containing the substrate. The vapor may beintroduced to the chamber at a flow rate ranging from approximately 0.1sccm to approximately 1 slm. For example, for a 200 mm wafer size, thevapor may be introduced to the chamber at a flow rate ranging fromapproximately 5 sccm to approximately 50 sccm. Alternatively, for a 450mm wafer size, the vapor may be introduced to the chamber at a flow rateranging from approximately 25 sccm to approximately 250 sccm. One ofordinary skill in the art will recognize that the flow rate will varyfrom tool to tool.

An inert gas is also introduced into the plasma reaction chamber inorder to sustain the plasma. The inert gas may be He, Ar, Xe, Kr, Ne, orcombinations thereof. The halide-containing compound and the inert gasmay be mixed prior to introduction to the chamber, with the inert gascomprising between approximately 0.1% v/v and approximately 99.9% v/v ofthe resulting mixture. Alternatively, the inert gas may be introduced tothe chamber continuously while short sprays of the halide-containingcompound are introduced to the chamber.

The halide-containing compound may be disassociated into radical formusing a plasma. The plasma may be ignited in the chamber containing thehalide-containing compound. Alternatively, the halide-containingcompound may be disassociated using a remote plasma system. The plasmamay be generated by applying RF or DC power. The plasma may be generatedwith a RF power ranging from about 25 W to about 10,000 W. The plasmamay be generated in Dual CCP or ICP mode with RF applied at bothelectrodes. RF frequency of plasma may range from 200 KHz to 1 GHz.Different RF sources at different frequency can be coupled and appliedat the same electrode. Plasma RF pulsing may be further used to controlmolecule fragmentation and reaction at substrate. One of skill in theart will recognize methods and apparatus suitable for such plasmatreatment.

Quadropole mass spectrometer (QMS), optical emission spectrometer, FTIR,or other radical/ion measurement tools may measure the activatedhalide-containing compound to determine the types and numbers of speciesproduced. If necessary, the flow rate of the halide-containing compoundand/or the inert gas may be adjusted to increase or decrease the numberof radical species produced.

The plasma may be maintained for a certain duration, which may beoptimized based on the characteristics of the layer to be removed.Applicants believe that the halide-containing compound reacts with thelayer to form an activated layer. The chamber is purged of any unreactedhalide-containing compound and volatile reaction products.

The vapor of a volatile organic compound is introduced into the chamber.The volatile organic compound may be alcohols, ethers, amines,hydrazines, diketones, carboxylic acids, aldehydes, ketoimines,diketimines, bis(silyl)amides, anhydrides, or combinations thereof.These volatile organic compounds are either commercially available ormay be synthesized by methods known in the art.

The volatile organic compounds may be in gas, liquid, or solid form atstandard temperature and pressure. As the term “gas” is synonymous withthe term “vapor,” the gas compounds may be directly introduced into thechamber.

If in liquid form, the volatile organic compound may be supplied eitherin neat form or in a blend with a suitable solvent, such as ethylbenzene, xylene, mesitylene, decane, or dodecane. The liquid volatileorganic compounds may be present in varying concentrations in thesolvent. One or more of the neat or blended liquid volatile organiccompounds are introduced into a reactor in vapor form by conventionalmeans, such as tubing and/or flow meters. The vapor form of the liquidvolatile organic compound may be produced by vaporizing the neat orblended compound solution through a conventional vaporization step suchas direct vaporization, distillation, or by bubbling. The neat orblended liquid may be fed in liquid state to a vaporizer where it isvaporized before it is introduced into the reactor. Alternatively, theneat or blended liquid may be vaporized by passing a carrier gas into acontainer containing the compound or by bubbling the carrier gas intothe compound. The carrier gas may include, but is not limited to, Ar,He, N₂, and mixtures thereof. Bubbling with a carrier gas may also helpremove any dissolved oxygen present in the neat or blended compoundsolution. The carrier gas and volatile organic compound are thenintroduced into the reactor as a vapor.

The vapour of the solid volatile organic compound may be supplied usinga sublimator, such as the one disclosed in PCT Publication WO2009/087609to Xu et al. Alternatively, the solid volatile organic compound may beblended with a suitable solvent, such as ethyl benzene, xylene,mesitylene, decalin, decane, dodecane. The volatile organic compound maybe present in varying concentrations in the solvent.

If necessary, the container of the volatile organic compound may beheated to a temperature that permits the compound to have sufficientvapour pressure in its gas, liquid, or solid phase. The container may bemaintained at temperatures in the range of, for example, approximately0° C. to approximately 150° C. Those skilled in the art recognize thatthe temperature of the container may be adjusted in a known manner tocontrol the amount of compound vaporized.

In one alternative, the volatile organic compound is anoxygen-containing compound. Applicants believe that, due to theoxophilic nature of Ti, the oxygen molecule will react with activatedsurface in the mask layer to produce a volatile M-O—R compound, with Mbeing Ti, Ta, W, or Al, and R being any ligand from theoxygen-containing compound. The volatile M-O—R compound will then beeasily removed from the chamber. The oxygen-containing compounds may bealcohols, ethers, diketones, carboxylic acids, aldehydes, anhydrides,ketoimines, or combinations thereof. Exemplary alcohols includemethanol, ethanol, isopropanol, and mixtures thereof. Exemplary ethersinclude dimethyl ether or diethyl ether. Exemplary diketones includeacetyl acetone and hexafluoroacetylacetone. Preferably, the diketone isacetyl acetone. Exemplary carboxylic acids include acetic acid.Exemplary aldehydes include formaldehyde or acetaldehyde. Exemplaryanhydrides include acetic anhydride. Exemplary enaminoketones include4-ethylamino-pent-3-en-2-one.

In another alternative, the volatile organic compound is anitrogen-containing compound. Applicants believe, due to the affinity ofM for N, that the nitrogen-containing compound will react with activatedsurface in the mask layer to produce a volatile M-N—R compound, with Mbeing Ti, Ta, W, or Cu, and R being any ligand from thenitrogen-containing compound. The volatile M-N—R compound will then beeasily removed from the chamber. The nitrogen-containing compounds maybe amines, amidinates, hydrazines, ketoimines, diketimines,bis(silyl)amides, or combinations thereof. Exemplary amines includemethylamine, dimethylamine, ethylamine, diethylamine, isopropylamine,and diisopropylamine. Exemplary amidinates includeN,N′-bis(1-methylethyl)-ethanimidiamide (CAS 106500-93-0). Exemplaryhydrazines include Me₂NNMe₂ or Et₂NNH₂. Exemplary ketoimines include4-ethylamino-pent-3-en-2-one. Exemplary diketimines includeN,N-diethylpentadiamine. Exemplary bis(silyl)amides have the formulaR₃Si—NH—SiR₃, wherein each R is independently selected from a C1 to C5alkyl group. One preferred bis(silyl)amide is bis(trimethylsilyl)amide.

In order to prevent surface changes on the substrate or any otherprocess inconsistencies, purity of the volatile organic compound isbetween approximately 99.99% v/v and approximately 100% v/v, preferablyapproximately 99.999% v/v and approximately 100% v/v. The concentrationof O₂ in the volatile organic compound is preferably betweenapproximately 0 ppmv and approximately 50 ppmv, preferably betweenapproximately 0 ppmv and approximately 4 ppmv, and more preferablybetween approximately 0 ppmv and approximately 1 ppmv. The concentrationof H₂O in the volatile organic compound is preferably betweenapproximately 0 ppmv and approximately 10 ppmv, preferably betweenapproximately 0 ppmv and approximately 2 ppmv, and more preferablybetween approximately 0 ppmv and approximately 1 ppmv.

The vapor of the volatile organic compound is introduced into the plasmareaction chamber containing the substrate. The vapor may be introducedto the chamber at a flow rate ranging from approximately 0.1 sccm toapproximately 1 slm. For example, for a 200 mm wafer size, the vapor maybe introduced to the chamber at a flow rate ranging from approximately 5sccm to approximately 50 sccm. Alternatively, for a 450 mm wafer size,the vapor may be introduced to the chamber at a flow rate ranging fromapproximately 25 sccm to approximately 250 sccm. One of ordinary skillin the art will recognize that the flow rate will vary from tool totool.

In one alternative, the disclosed volatile organic compounds may be usedto react with and remove the activated layer in a thermal process. Inthis process, the substrate is kept at a high temperature (approximately−50° C. to approximately 400° C.). These temperatures may be sufficientto allow the vapor of the volatile organic compounds and the activatedlayer to react and produce volatile by-products.

In another alternative, the disclosed volatile organic compounds may beused to remove the activated layer in a plasma process. The vapor of thevolatile organic compound may be disassociated into radical form using aplasma. The plasma may be ignited in the chamber containing the volatileorganic compound. Alternatively, the volatile organic compound may bedisassociated using a remote plasma system. In this process, an inertgas is also used in order to sustain the plasma. The inert gas may beHe, Ar, Xe, Kr, Ne, or combinations thereof. The volatile organiccompound and the inert gas may be mixed prior to introduction to thechamber, with the inert gas comprising between approximately 50% v/v andapproximately 95% v/v of the resulting mixture. Alternatively, the inertgas may be introduced to the chamber continuously while short sprays ofthe volatile organic compound are introduced to the chamber. Asdiscussed with respect to the halide-containing compound, the plasma maybe ignited by applying RF or DC power. Alternatively, no plasma may beused, particularly when the volatile organic compound is sufficientlyreactive so that no plasma is required.

The plasma may be maintained for a certain duration, which may beoptimized based on the characteristics of the activated layer to beremoved. Applicants believe that the volatile organic compound reactswith the activated layer. The chamber is purged of any unreactedvolatile organic compound and any volatile reaction products.

The disclosed processes preferably selectively etch the metal layer ormask material from surrounding silicon-containing, such as low k or SiN,or metal conducting layers, such as Co or Ni. The disclosed processeswill be much more economically friendly than the prior liquid etchprocesses because they may be performed in the same chamber where vapordeposition and other vapor etch processes are performed. The disclosedprocesses may also result in faster throughput. Alternatively, thedisclosed processes may provide discrete self-limiting steps providinginfinite selectively between the layer being etched and its surroundinglayers. The disclosed process may solve the metal etching challenges invacuum environment, with currently available solutions limited tosputtering or Ion milling

EXAMPLES

The following non-limiting examples are provided to further illustrateembodiments of the invention. However, the examples are not intended tobe all inclusive and are not intended to limit the scope of theinventions described herein.

The test results in comparative examples 1-5 and examples 1-3 and 5 thatfollow were obtained using the R&D chamber 100 illustrated in FIG. 3.The test results in comparative examples 6 and 7 and example 4 wereobtained using the R&D chamber 100 illustrated in FIG. 29. The chambers100 include a gas showerhead 105 and a thermally conductive plate 110. Agas inlet 101 and an RF source 106 are connected to the gas showerhead105 in FIG. 3. The RF source 106 is connected to the conductive plate inFIG. 29. A heater 111 and temperature sensor 112 are connected to thethermally conductive plate 110. The chamber 100 also includes a gasoutlet 102. The gas outlet 102 is connected to a pump (not shown). A gassample outlet 103 is also located in the chamber 100 and connected to amass spectrometer (not shown) for analysis of gas species in the chamber100. Double sided carbon tape (not shown) was used to adhere anapproximately 8 mm×8 mm Si substrate to the showerhead 105 (the “topsample T”). An approximately 8 mm×8 mm Si substrate was placed on thethermally conductive plate 110 (the “bottom sample B”). A TiN layerapproximately 55 nm thick was used for each of T and B in ComparativeExamples 1-5 and Examples 1, 2 and 5. Pressure in the chamber 100 wasmaintained from 0.2 Torr to 0.6 Torr during the etch processes and at 1Torr during the nitrogen purge. The walls of the chamber 100 andshowerhead 105 are cooled by water to approximately 22° C., although thethermally conductive plate 110 was heated to high enough temperatures toheat the walls and showerhead 105 above 22° C. (the thermally conductiveplate 110 was heated to approximately 250° C., to be more precise,unless stated otherwise). The chamber 100 did not include a loadlock(i.e., samples T and B were exposed to air during mounting and removalafter etching). As a result, the chamber 100 was purged for 1 hour withthe thermally conductive plate 110 heated to the process temperature(between 25° C. and 400° C.) in order to minimize moisture levels afterthe samples T and B were placed in the chamber 100. One of ordinaryskill in the art will recognize that similar or different chambers maybe used without departing from the teachings herein.

The research chamber 100 of FIG. 3 does not include a RF powered andheated bottom electrode/thermally conductive plate 110. The chamber onlyhas heated bottom electrode/thermally conductive plate 110 (it isgrounded). The gas outlet is connected to a Fomblin oil pump which isinert to O₂ so it doesn't catch fire (commercial embodiments are morelikely to use a dry pump). The thermally conductive plate 110 sees someion bombardment, but minor. The showerhead 105 is not at roomtemperature, but has good ion bombardment. Another research chambershown in FIG. 29, which was only used to produce the data from Example4, was designed to allow RF and temperature capability on the sameelectrode. One of ordinary skill in the art will recognize that furtheroptimization of the results below will be obtained when transferred tocommercial, rather than R&D, systems.

The test results in the examples that follow were obtained usingellipsometry, scanning electron microscopy (SEM), energy dispersivex-ray spectroscopy (EDS), or 2 probe resistance measurements (MDC VacuumProducts probe setup and Keithley Instruments multimeter). The SEM filmthickness results reported below have a ±10 nm margin of error due tomeasurement limitations. The EDS spectrum for the starting TiN layer onthe silicon substrate is provided in FIG. 4. As is evident, thequalitative presence of Ti is seen at its expected energy numbers around0.5 keV and 4.5 keV of the EDS spectrum. The N peak overlaps with the Tipeak at 0.5 keV, making the N determination impossible. The initial TiNfilm has resistance of 90 ohms for a film having an approximately 55 nmthickness.

As will be evident, only the chemistry and application of plasma wasvaried in the examples that follow. Except for comparative examples 6and 7, the plasma wattage, thermally conductive plate 110 temperature,thermally conductive plate 110 and showerhead 105 distance (i.e.,electrode distance), etc., did not change, but may be varied for furtherprocess optimization.

Comparative Example 1 TiN Etch Using Cl₂No Plasma

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 for 300 seconds. Thethermally conductive plate 110 was maintained at 250° C. No plasma wasignited. SEM analysis revealed a TiN film thickness of 49±3 nm for the Tsample and 50±1 nm for the B sample. The resistance of the TiN film was85-89 Ohms for the T sample and 99-102 Ohms for the B sample. The EDSspectrums for the T film is provided in FIG. 5 and for the B film isprovided in FIG. 6. As is evident from these results, little or noetching of the TiN film occurs using Cl₂ without plasma.

Comparative Example 2 TiN Etch Using Cyclic Cl₂ with Plasma

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and then purged by a30 second N₂ flow. The process was repeated for 100 cycles.

SEM analysis revealed a TiN film thickness of 53±2 nm for the T sampleand 54±0 nm for the B sample. The resistance of the TiN film was 97-99Ohms for the T sample and 105-108 Ohms for the B sample. As is evidentfrom these results, little or no etching of the TiN film occurs usingCl₂ with plasma.

Comparative Example 3 TiN Etch Using EtOH No Plasma

Approximately 50 sccm Ar and approximately 5 sccm ethanol (EtOH) wereintroduced through the showerhead 105 into the chamber 100 for 65minutes. The thermally conductive plate 110 was maintained at 250° C.The vacuum of the chamber 100 was used to pull the EtOH vapor from theheadspace of the EtOH container (not shown) and introduce it to thechamber 100. The thermally conductive plate 110 was maintained at 250°C. No plasma was ignited. SEM analysis revealed a TiN film thickness of52±1 nm for the T sample and 48±0 nm for the B sample. The resistance ofthe TiN film was 85 Ohms for the T sample and 101-102 Ohms for the Bsample. As is evident from these results, little to no etching of theTiN film occurs using EtOH without plasma.

Comparative Example 4 TiN Etch Using Cyclic EtOH with Plasma

Approximately 50 sccm Ar and approximately 5 sccm EtOH were introducedfor 90 seconds through the showerhead 105 into the chamber 100. Thethermally conductive plate 110 was maintained at 250° C. After 60seconds of introduction in order to provide gaseous equilibrium, theplasma was ignited (300 W) for 30 seconds. The thermally conductiveplate 110 was maintained at 250° C. The chamber 100 was evacuated andpurged by a 30 second N₂ flow. The process was repeated for 100 cycles.

SEM analysis revealed a TiN film thickness of 59±1 nm for the T sampleand 55±1 nm for the B sample. The resistance of the TiN film was 87-89Ohms for the T sample and 94-95 Ohms for the B sample. As is evidentfrom these results, little or no etching of the TiN film occurs usingEtOH with plasma.

Comparative Example 5 TiN Etch Using CF₄

Approximately 50 sccm Ar and approximately 50 sccm CF₄ were introducedthrough the showerhead 105 into the chamber 100. Pressure in the chamberwas approximately 0.5 Torr. The thermally conductive plate 110 wasmaintained at 250° C. The plasma was ignited by 400 W. FIG. 7 is a SEMphoto taken after 300 seconds reveal that the TiN layer was peeling.Peeling is detrimental in etch processes because the progression of thematerial removal process is not linear and not predictable. In addition,peeling removes material in larger sizes than individual molecules,e.g., particulates. Particulates may or may not exit the chamber and, ifremaining inside the chamber, may fall onto the wafer and cause defectson the device.

Comparative Example 6 Ni, Co, Pd, or Fe Etch Using Cyclic Cl₂

In this example, four approximately 8 mm×8 mm Si (100) substratescontaining an approximately 15 nm Ti layer were placed on the thermallyconductive plate 110. Each substrate had an approximately 100 nm layerof Ni, Co, Pd, or Fe on top of the Ti layer.

Approximately 30 sccm Ar and approximately 5 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(0, 100, or 200 W) for 10 seconds. The thermally conductive plate 110was maintained at 100° C. or 240° C. The chamber 100 was evacuated andthen purged by a 30 second N₂ flow. The process was repeated for 100cycles.

The results at 240° C. are summarized in FIG. 30. The results at 100° C.are summarized in FIG. 31. As illustrated therein, Fe was completelyetched at 100 W and 200 W at both 100° C. and 240° C., but not at 0 W ateither temperature. Cobalt was etched at 200 W at 100° C. and 240° C.,but not (or negligibly) at 0 or 100 W. Pd and Ni had no to negligibleetching under all conditions.

Comparative Example 7 Ni, Co, Pd, or Fe Etch Using CyclicAcetylacetonate

In this example, four approximately 8 mm×8 mm Si (100) substratescontaining an approximately 15 nm Ti layer were placed on the thermallyconductive plate 110. Each substrate had an approximately 100 nm layerof Ni, Co, Pd, or Fe on top of the Ti layer.

Approximately 30 sccm Ar and approximately 30 mTorr (partial pressure)of Acac were introduced through the showerhead 105 into the chamber 100and the plasma ignited (200 W) for 10 seconds. The thermally conductiveplate 110 was maintained at 240° C. The chamber 100 was evacuated andthen purged by a 30 second N₂ flow. The process was repeated for 25 or100 cycles.

The results at are summarized in FIG. 32. As illustrated therein, aconstant etch rate was observed for Pd. Co exhibited no etching at 25cycles but approximately 50 nm of Co was removed after 100 cycles,demonstrating some kind of incubation effect. Little to no etching of Feor Ni occurred.

Example 1 TiN Etch

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 5 sccm EtOHwere introduced for 90 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated for 100 cycles.

SEM analysis revealed a TiN film thickness of 0 nm for both the T and Bsamples. The resistance of the TiN film was 0.2M-0.7M Ohms for the Tsample and 0.018M Ohms for the B sample. The EDS spectrums for the Tfilm is provided in FIG. 8 and for the B film is provided in FIG. 9. Asis evident from these results, little to no TiN film remains afterperforming the disclosed etching process.

Example 2 TiN Etch

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 5 sccm EtOHwere introduced for 90 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated for 10 cycles. The EDS spectrum for the B film is providedin FIG. 10.

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 5 sccm EtOHwere introduced for 90 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated for 20 cycles. The EDS spectrum for the B film is providedin FIG. 11.

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 5 sccm EtOHwere introduced for 90 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated for 30 cycles. The EDS spectrum for the B film is providedin FIG. 12.

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 5 sccm EtOHwere introduced for 90 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated for 40 cycles. The EDS spectrum for the B film is providedin FIG. 13.

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 5 sccm EtOHwere introduced for 90 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated for 50 cycles. The EDS spectrum for the B film is providedin FIG. 14.

As can be seen from FIGS. 10-14, the amount of Ti in the TiN layerdecreased as the number of cycles increased, illustrating the epitaxialnature of the removal process. The results of Comparative Examples 2 and4 and Example 2 are summarized in FIG. 15.

Example 3 Fe and Pd Etch Using Cl₂ and Ethanol (EtOH)

In this example, double sided carbon tape (not shown) was used to adherean approximately 8 mm×8 mm Si (100) substrate containing anapproximately 15 nm Ti layer with an approximately 100 nm Pd layerdeposited thereon (in other words Pd/Ti/Si) to the showerhead 105 (the“top sample T”). An approximately 8 mm×8 mm Si (100) substratecontaining an approximately 15 nm Ti layer with an approximately 100 nmFe layer deposited thereon (in other words Fe/Ti/Si) was placed on thethermally conductive plate 110.

Approximately 50 sccm Ar and approximately 20 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 10 sccm EtOHwere introduced for 30 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated.

FIG. 16 is a spectrum obtained by EDS of the Fe layer before etching.FIG. 17 is a spectrum obtained by EDS of the Fe sample after exposure to15 cycles of Cl₂ with plasma followed by ethanol with plasma. FIG. 18 isa spectrum obtained by EDS of the Fe sample after exposure to 30 cyclesof Cl₂ with plasma followed by ethanol with plasma. FIG. 19 is aspectrum obtained by EDS of the Fe sample after exposure to 45 cycles ofCl₂ with plasma followed by ethanol with plasma. FIG. 20 is a spectrumobtained by EDS of the Fe sample after exposure to 74 cycles of Cl₂ withplasma followed by ethanol with plasma. FIG. 21 is a spectrum obtainedby EDS of a comparative Fe sample subject to 100 cycles of Cl₂ withplasma. As can be seen from FIGS. 17-20, the amount of Fe in the layerdecreased as the number of cycles increased. Comparing with Cl₂ etchingin FIG. 21 alone, ethanol was critical to enhance the etching over Cl₂alone.

FIG. 22 is a spectrum obtained by EDS of the Pd layer before etching.FIG. 23 is a spectrum obtained by EDS of the Pd sample after exposure to15 cycles of Cl₂ with plasma followed by ethanol with plasma. FIG. 24 isa spectrum obtained by EDS of the Pd sample after exposure to 30 cyclesof Cl₂ with plasma followed by ethanol with plasma. FIG. 25 is aspectrum obtained by EDS of the Pd sample after exposure to 45 cycles ofCl₂ with plasma followed by ethanol with plasma. FIG. 26 is a spectrumobtained by EDS of the Pd sample after exposure to 74 cycles of Cl₂ withplasma followed by ethanol with plasma. FIG. 27 is a spectrum obtainedby EDS of a comparative Pd sample subject to 100 cycles of Cl₂ withplasma. As can be seen from FIGS. 23-26, the amount of Pd in the layerdecreased as the number of cycles increased. Comparing with Cl₂ etchingin FIG. 27 alone, ethanol was critical to enhance the etching over Cl₂alone.

Example 4 Etch Using Cl₂ and Acetylacetonate (Acac)

In this example, four approximately 8 mm×8 mm Si (100) substratescontaining an approximately 15 nm Ti layer were placed on the thermallyconductive plate 110 in the modified chamber of FIG. 29. Each substratehad an approximately 100 nm layer of Ni, Co, Pd, or Fe on top of the Tilayer.

Approximately 30 sccm Ar and approximately 5 sccm Cl₂ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(200 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 240° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 30 sccm Ar and approximately 30 mTorrpartial pressure of acetylacetonate were introduced through theshowerhead 105 into the chamber 100. After 60 seconds of introduction inorder to provide gaseous equilibrium, the plasma was ignited (200 W) for30 seconds. The chamber 100 was evacuated and purged by a 30 second N₂flow.

The Cobalt film was etched at a rate of approximately 1.6 nm/cycle. TheIron film was etched at a rate of approximately 1 nm/cycle. No etchingof the Ni film occurred. The Pd film was etched at a rate ofapproximately 1.25 nm/cycle.

Additional testing was performed comparing the etch rate for 25 cyclesvs. 100 cycles. Both Co and Pd exhibited similar etch rates, indicatingcontrollable, repeatable results. The iron etch rate was 4 times higherafter 25 cycles than it was after 100 cycles, indicating that etchingoccurs faster during the first few cycles.

FIG. 28 is a graph comparing the Pd etch rate (in nm/cycle) from acyclic Cl₂ etch process alone, a cyclic acetylacetonate etch processalone, and a cyclic etch process using both Cl₂ and acetylacetonate.FIG. 28 shows Cl₂ alone cannot remove the Pd film, Acac alonesuccessfully etched Pd when used alone at the conditions listed, andthat the cyclic combination of Cl₂ and Acac produced unexpectedsynergistic effects over the process for either Cl₂ or Acac alone.

Based on these results, one of ordinary skill in the art would expectother elements to behave similarly to Pd based on the prioracetylacetonate (acac) cycle data (cite Jane Chang citing S. W. Kang etal., JVST B, 17 (1999) 154 showing acac Fe, Ni, and Cu forms M(acac)₂and acac tfac and hfac also work with Ni (R. I. Masel et al. JVST A. 16(1998) 3259).

Example 5 TiN Etch with Ar/CF₄

Approximately 50 sccm Ar and approximately 10 sccm CF₄ were introducedthrough the showerhead 105 into the chamber 100 and the plasma ignited(300 W) for 10 seconds. The thermally conductive plate 110 wasmaintained at 250° C. The chamber 100 was evacuated and purged by a 30second N₂ flow. Approximately 50 sccm Ar and approximately 5 sccm EtOHwere introduced for 90 seconds through the showerhead 105 into thechamber 100. After 60 seconds of introduction in order to providegaseous equilibrium, the plasma was ignited (300 W) for 30 seconds. Thechamber 100 was evacuated and purged by a 30 second N₂ flow. The processwas repeated for 100 cycles.

SEM analysis revealed a TiN film thickness on top mounted sample (T),reduced from ˜55 nm to ˜40 nm after 100 cycles. Bottom sample had nofilm remaining. Too high a temperature at the bottom electrode may havelead to Ti/Si interface loss and potential peeling. The lowertemperature of the top electrode combined with ethanol has showncontrolled etching of TiN. Further experiments as a function of cyclescan be repeated to validate further.

It will be understood that many additional changes in the details,materials, steps, and arrangement of parts, which have been hereindescribed and illustrated in order to explain the nature of theinvention, may be made by those skilled in the art within the principleand scope of the invention as expressed in the appended claims. Thus,the present invention is not intended to be limited to the specificembodiments in the examples given above and/or the attached drawings.

We claim:
 1. A method of removing a material from a substrate, themethod comprising: (a) introducing a vapor of a halide-containingcompound into a chamber containing the substrate having the materialdisposed thereon; (b) igniting a plasma in the chamber; (c) purging thechamber; (d) introducing a vapor of a volatile organic compound into thechamber; and (e) purging the chamber.
 2. The method of claim 1, furthercomprising repeating steps (a) through (e).
 3. The method of claim 1,further comprising igniting a plasma after introduction of the vapor ofthe volatile organic compound.
 4. The method of claim 3, furthercomprising repeating the halide-containing compound introduction,ignition, purging, volatile organic compound introduction, ignition, andpurging steps.
 5. The method of claim 1, wherein the material isselected from the group consisting of Ti, Ta, W, Al, Pd, Ir, Co, Fe, B,Cu, Ni, Pt, Ru, Mn, Mg, Cr, Au, alloys thereof, oxides thereof, nitridesthereof, and combinations thereof.
 6. The method of claim 1, wherein thehalide-containing compound is selected from the group consisting of F₂,Cl₂, Br₂, I₂, FCl, ClF₃, BCl₃, BBr₃, BF₃, BI₃, HCl, HBr, HI, CF₄, CH₂F₂,CHF₃, CF₃I, CF₃Br, FNO, NF₃, SOCl₂, SO₂Cl₂, and combinations thereof. 7.The method of claim 1, wherein the volatile organic compound is selectedfrom the group consisting of alcohols, ethers, amines, hydrazines,diketones, carboxylic acids, aldehydes, ketoimines, diketimines,bis(silyl)amides, anhydrides, amidinates, and combinations thereof. 8.The method of claim 7, wherein the amidinate isN,N′-bis(1-methylethyl)-ethanimidiamide (CAS 106500-93-0).
 9. The methodof claim 7, wherein the alcohol is selected from the group consisting ofmethanol, ethanol, and isopropanol.
 10. The method of claim 7, whereinthe ether is dimethyl ether or diethyl ether.
 11. The method of claim 7,wherein the amine is selected from the group consisting of methylamine,dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine,isopropylamine, diisopropylamine, triisoproylamine, and combinationsthereof.
 12. The method of claim 7, wherein the hydrazine is Me₂NNMe₂ orEt₂NNH₂.
 13. The method of claim 7, wherein the diketone is acetylacetone or hexafluoroacetylacetone.
 14. The method of claim 7, whereinthe diketone is acetyl acetone.
 15. The method of claim 7, wherein thecarboxylic acid is acetic acid.
 16. The method of claim 7, wherein thealdehyde is formaldehyde or acetaldehyde.
 17. The method of claim 7,wherein the ketoimine is 4-ethylamino-pent-3-en-2-one.
 18. The method ofclaim 7, wherein the diketimine is N,N-diethylpentadiamine.
 19. Themethod of claim 7, wherein the bis(silyl)amide has the formulaR₃Si—NH—SiR₃, wherein each R is independently selected from a C1 to C5alkyl group.
 20. The method of claim 19, wherein the bis(silyl)amide isbis(trimethylsilyl)amide.
 21. The method of claim 7, wherein theanhydride is acetic anhydride.
 22. The method of claim 1, whereinperforming steps (a) through (e) one time removes one atomic layer ofthe material.